Automatic block signaling system for railroads



Dec. 24, 1940. s. r. CALLAHAN AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAILROADS Filed Oct, 15, 19358 2 Sheets-Sheet l NVENTOR i ATTORNEY Dec. 24, 1940.

G. T. CALLAHAN AUTOMATIC BLOCK SIGNALING SYSTEM FOR RATLROADS Filed Get. 15. 1938 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAILROADS ter, N. Y.

Application October 15, 1938, Serial No. 235,255

10 Claims.

This invention relates to automatic block signaling systems for single track railroads of the type commonly known as absolute-permissiveblock systems, and more particularly pertains to such systems employing five indication signals.

In the usual absolute-permissive-block system, such as disclosed, for example, in-the patent to S. N. Wight, No. 1,294,736, dated February 18,

' 1919, after a train enters a stretch of single track the tumble-down of all of the line relays for the opposing signals for that stretch of track renders the line circuits for those relays deenergized and idle. This invention makes use of certain ones of the line wires in such idle line circuits for providing that the intermediate signals shall each give an indication in addition to the usual four indications.

Thus five distinctive indications are provided for each signal, namely; a clear indication is provided when one wire of the line circuit for that signal is energized together with one of the idle line wires for an opposing signal; an approach-medium indication is provided when the line circuit for that signal is energized positive; an approach indication is provided when the line circuit for that signal is energized negative; a stop-and-proceed indication is provided when the line circuit for that signal is deenergized, and its stick relay is energized; and an absolute stop indication is provided when the line circuit and the stick relay for that signal is deenergized.

Other objects, purposes and characteristic features of the invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention in detail reference will be made to Figs. 1A and 1B, which, when placed end to end, constitute a plan showing one embodiment of the present invention, and in which like reference characters (provided with distinctive exponents or. preceding numerals) designate similar parts throughout both drawmgs.

With reference to the accompanying drawings, a stretch of single track has been shown having signals associated therewith for governing traflic in both directions, of which signals 5 S S and S have been shown for governing east-bound traihc, toward the right; and signals S S", S and S have been shown governing west-bound traffic, toward the left.

The stretch of track is divided into blocks,

each of which is composed of two track sections insulated from each other by the usual insulated joints, and each track section having a track relay energized from the track battery by the usual track circuit, of which track relays 2TB, 4TA, 4TB, ETA, 6TB, '8TA, 8TB, and IOTA have been shown.

The signals have been shown as being of the color position light type, having in addition to the position light signal unit, a white lamp W directly above the unit and another white lamp W above and to the left of the unit. Such a combination of signal lamps provides the following distinctive indications. The illumination of two green lamps G, one above the other, in combination with the illumination of the white lamp W directly above the unit, provides a clear indication. The illumination of two green lamps G, one above the other, in combination with the illumination of the white lamp W above the unit and to the left, provides an approach-medium indication. The illumination of two yellow lamps Y, one above the other and at a 45 angle to the right, in combination with the illumination of the white lamp W directly above the unit, provides an approach indication. The illumination of two red lamps R, both in a horizontal plane, in combination with the illumination of the white lamp W directly above the unit, provides .a stop-and-proceed indication. The illumination of two red lamps R, both in a horizontal plane, with both of the white lamps W and 'W extinguished, provides an absolute-stop indication. It is of course to be understood that other means for displaying the indications could as well be employed, all within the scope of the present invention.

The relays I-ID, PC and S are of the type commonly employed in absolute-permissiveblocl; signaling, and the control of these relays is well known to those familiar with the art.

The relay AD is a neutral type relay which is used for selecting the control of the white lamps, and the control circuit for this relay includes one of the line wires used for controlling the HD relay associated with the control of an opposing signal.

For the purpose of simplifying the illustration and facilitating in the explanation thereof the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of facilitat- .ing the disclosure as to the principles and mode of operation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and the contacts have been illustrated in the conventional manner and symbols are used to indicate connection to the terminals of batteries, or other sources of electric current, instead of showing all of the wiring connections to these terminals.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries, or other sources of direct current, and the circuits with which those symbols are used always have current flowing in the same direction.

It is believed that novel features of this invention can best be understood by considering operation of the system during the passage of trains.

Operation In view of the fact that the apparatus for each signal location is similar to that used at other locations, in order to simplify the disclosure, conditions of the apparatus at certain signal locations under various traffic conditions will be described in detail, and these conditions are to be considered as typical of conditions which exist under similar traffic conditions at any of the other signal locations.

Under normal conditions, with the track section unoccupied the relay HD for each signal is energized over a line circuit extending to the next signal in advance for governing traffic in the same direction; as, for example, relay GHD is energized by a circuit closed from through back contact of relay 98, front contact 2| of relay 8P0, front contact 22 of relay 6TB, wire 23, front contact 24 of relay 6TA, winding of relay EHD, wire 25, front contact 26 of relay 6TB, front contact 21 of relay 8P0, and back contact 28 of relay 9AD, to

When relay fiI-ID is picked up, a circuit is closed for energizing relay 6P0 from through front contact 29 of relay BHD and winding of relay SPC, to

Under normal conditions the relays 6S and GAD are deenergized, and a circuit is closed for energizing the white lamp W in signal S from through front contact 30 of relay BPC, polar contact 3! of relay BHD in a right-hand position, back contact 32 of relay GAD and lamp W to At the same time a circuit is closed for energizing the green lamps G in signal S from through front contact 33 of relay BPC, polar contact 34 of relay 6HD in a righthand position, and both of the lamps G connected in multiple, to

Thus, under normal conditions with the track circuits for the stretch of single track unoccupied each signal displays an approach medium indication if approach lighting for the signal lamps is not provided.

In order that the drawings can clearly show the conditions of the relays under various traffic conditions an east-bound train K has been shown as having entered block I0, and, due to the fact that the idle line wire for the control of the relay HD for an opposing signal is used to govern the clear indication of a signal, it has been necessary to show a second east-bound train K approaching signal S in block 2, in order to show all four proceed indications in a successive order as they are provided in practice. If the second train K were not present the relay 5HD would be n its energized condition, resulting in the picking up of relay 5P0, thereby opening the circuit for the relay 4AD at back contact 46. Dropping of relay 4AD would close the energizing circuit for relay IHD, and so on, causing all of the west bound signals of that single track section to the rear of train K to give an approachmedium indication.

When a train approaches a signal, if the first three blocks in advance of that signal are unoccupied, a clear indication is provided for that train by the illumination of two green lamps G, one above the other, in combination with the illumination of the white lamp W directly above the position light unit, such as is shown for signal S when the train K is approaching that signal.

Under the conditions shown at signal S relay 4HD is energized with positive energy to operate its polar contacts to a right-hand position, by a circuit closed from through back contact 35 of relay IS, front contact 36 of relay BPC, front contact 31 of relay 4TB, front contact 38 of relay 4TA, winding of relay 4HD, front contact 39 of relay 4TB, front contact 40 of relay SP0, and back contact 4| of relay 4AD, to

Relay 4AD is also energized, under the conditions shown, from the next signal in advance which is S over a line circuit including one of the line wires used for the control of relay 4HD and one of the line wires used for the control of relay II-ID. Relay 4AD is energized by a circuit closed from through back contact 35 of relay 1S, front contact 36 of relay GPC, polar contact 42 of relay GHD in a right-hand position, front contact 43 of relay GHD, back contact 44 of relay II-ID, front contact 45 of relay 4TA, back contact 46 of relay 5P0, back contact 41 of relay 5S, winding of relay 4AD, front contact 48 of relay 4HD, front contact 39 of relay 4TB, front contact 40 of relay GPC, and back contact 4| of relay 'IAD, to

It will be noted in tracing the circuit for relay 4AD that the circuit included a polar contact 42 on relay BHD in a right-hand position, which provides that relay 4AD can be energized only when signal S is either clear or at approach medium, and that the circuit also includes a selection of a back contact 44 on relay II-ID to open the circuit for relay 4AD whenever the line circuit for the opposing signal is being used.

Relay 4PC is energized by a circuit closed from through a circuit including front contact 49 of relay 4HD and winding of relay 4PC to and the picking up of relay 4PC closes a circuit, for energizing the green lamps G in signal S from through front contact 59 of relay 4PC, polar contact 5| of relay 4HD in a right-hand position, and both of the green lamps G, connected in multiple, to At the same time a circuit is closed for energizing the white lamp W in signal 8*, from through front contact 52 of relay 4PC, polar contact 53 of relay 4HD in a right-hand position, front contact 54 of relay 4AD and white lamp W, to

Assume the train K to have advanced in an easterly direction to section [0, having passed signals S S S and S and to have caused the dropping of relay IOTA by having shunted its track circuit. The dropping of track relay IUTA opens the control circuit for relay lElI-ID at front contact 55, and the dropping of relay [GI-ID opens the control circuit for relay IOPC at front contact 56.

The stick relay, IOS is energized in the usual manner, it being picked up when relay IDTA drops and before relay MPG drops away, at

which time a circuit is closed from through back contact 51 of relay IOTA, front contact 58 of relay MP and winding of relay IDS, to and the picking up of that relay closes a stick circuit through front contact 59 :to shunt out contact 58 of relay IDPC.

The red lamps R for signal S are energized under the above conditions by a circuit closed from through back contact'fifl of relay IOPC and both of the red lamps R connected in multiple, to and at the same time a circuit is closed for energizing the white lamp W for that same signal, from through front contact Bl of relay Ills and white lamp W, to

Had the train K been proceeding in a westerly direction through track section I0, it :is obvious that the circuit for the control of the white lamp W would have been opened atfront contact SI of relay IBS, thus causing thesignal to display an absolute-stop indication by illuminating the red lamps B only, in a manner shown for each of the opposing signals S S", S and S With relay lilPC in a dropped awayposition, a circuit is closed for energizing relay 8HD, for the next signal in the rear, with negative polarity so as to cause the operation of its polar armature to its left-hand position, from through back contact 62 of relay llS,'front contact 63 of relay 108, back contact 64 of relay IUPC, front contact 65 of relay 8TB, winding of relay 8HD, front contact 66 of relay 8TA, front contact 61 of relay 8TB, back contact 68 of relay MP0 .and

back contact 69 of relay HAD, to

The picking up of relay 8HD closes a circuit for energizing relay 8PC from through front contact of relay 8HD and winding of relay 8P0, t0

The above conditions cause the display of an approach indication at signal S by the energization of the yellow lamps Y, from through a circuit including front contact 1! of relay BPC, polar contact 12 of relay BHD in a left-hand position, and both of the lamps Y connected in multiple, to and at the same time the white lamp W is energized from through a circuit including front contact 13 of .relay 8P0, polar contact M of relay BI-ID, in a left-hand position, and white lamp W, to

The picking up of relay 8P0 closes a circuit for energizing relay BHD with positive polarity, to operate its polar armature to a right-hand position, in the same manner as has heretofore been described for the control of that relay. The

picking up of relay 6I-ID caused the energization of relay SP0 and circuits are closed for energizing the green lamps G and the white lamp W for signal S through circuits which have already been described, the lamp W having been illuminated because the circuit for the control of relay has beenenergized as a result of which the home relay associated with such second signal is energized by current of reverse polarity, and the third signal in the rear of the'train is energized to give :a green indication because the home relay and its associated pole changer relay of the signal next in advance of such third signal is energized. It will also belseen that the fourth signal to the rear of a train will give the same indication insofar as the green, yellow and red lamps are concerned as the third signal in the rear. Referring now to the two white lamps W and W it will be seen that the lamp W can be energized only if either the associated stick relay S is energized (see signal S if the associated pole changer relay PC and the associated relay AD are energized and the polar contacts of the home relay are in their normal position (see signal S or the pole-changer relay is energized with the polar contacts of the home relay in their reverse polarity position (see signal S Also, it will be seen that the white lamp W can be energized only if the associated home relay is energized by current of reverse polarity, the associated pole changer relay is energized and the associated relay AD is deenergized, (see signal S that if the train K (see Fig. 1A) were not present in block 2 the relay 5HD would be energized instead of deenergized, resulting in the energization of the relay 5P0. Also, if this relay SP0 is energized the circuit for energizing the relay 4AD would be broken at the back contact 46 of relay 5P0 so that the lamp W would be energized instead of the lamp W. Stating it differently, the fourth or clear indication to the rear of a train is not given at the fourth signal to the rear of such train unless there is a train approaching such fourth signal. down circuits for one direction of travel produces the effect of an approach control for the other direction of travel. Also upon entrance of a train into a single track section, and the deenergization of all the home relays for the reverse direction of travel by the deenergization of the tumble-down circuits, the signals for this In other words, thetumble- From this consideration it is apparent reverse direction of travel will have both of their white lights deenergized thereby giving absolutestop indications. This is true because both the pole changer relay and the directional stick relay for each of these signals are both deenergized, thus removing all energy from the white light circuits.

Having described the control of certain doublev intermediate signals fora stretch of single track as one specific embodiment of the present invention, it is desired that it be understood that this form is selected to facilitate the description of the invention rather than to limit the number of forms which it may assume, and it is to be further understood that various modifications, adaptations and alterations may be applied to the specific forms shown to meet the requirements of practice, without departing in any manner from the spirit or scope of the present invention except as limited by the appended claims.

What I claim is:

1. In a block signaling system for railroads; a stretch of single track having signals for governing traflic in both directions; a polar-neutral relay for each signal; circuit means including line wires extending to the next signal in advance for governing traflic in the same direction for energizing said polar-neutral relay in accordance with the distinctive polarity of energization of such line wires from a source of current at such signal in advance; a neutral relay for each signal; circuit means for energizing said neutral relay, only if the polar-neutral relay at the next signal in advance for governing trafiic in the same direction is energized by current of a particular polarity, said circuit means including a line wire for controlling the polarneutral relay for an opposing signal, and being closed only if the polar-neutral relay for that opposing signal is in a dropped away position; and circuit means including contacts of said polar-neutral and said neutral relays for causing each signal to display a distinctive indication when said polar-neutral relay and said neutral relay for that signal are both picked up.

2. In a block signaling system for railroads; a stretch of single track having signals for governing traflic in both directions, a polar-neutral relay for each signal; circuit means for energizing said polar-neutral relay including line wires extending to the next signal in advance governing traflic in the same direction and energized by current of one or another polarity; circuit means including contacts of said polar-neutral relay for causing each signal to indicate approach-medium when the polar-neutral relay for that signal is energized by current of one polarity; a circuit means including contacts of said polar-neutral relay for causing each signal to indicate approach when the polar-neutral relay for that signal is energized by current of the opposite polarity; circuit means including contacts of said polar-neutral relay for causing each signal to indicate stop when the circuit for the control of the polar-neutral relay for that signal is open; a neutral relay for each signal; circuit means including contacts of the polar-neutral relay at the signal in advance for energizing each of said neutral relays when the signal in advance for governing trafilc in the same direction indicates clear or approach--medium, providing there is a train in said stretch of single track approaching the signal under consideration, through a circuit including a line wire for the control of a polarneutral relay for an opposing signal; and circuit means including contacts of said polar-neutral relay and said neutral relay for causing each signal to indicate clear when said polar-neutral relay and said neutral relay for that signal are both picked up.

3. In an absolutepermissive-block signaling system for railroads, a stretch of single track having signals for governing traflic in both directions; a polar-neutral relay for each signal; circuit means including line wires for energizing said polar-neutral relay in accordance with the distinctive polarity of energization of said line wires, said line wires extending to the next signal in advance for governing traffic in the same direction; circuit means including contacts of said polar-neutral relay for causing each signal to indicate approach-medium when the line wires for that signal are energized by current of one polarity; circuit means including contacts of said polarneutral relay for causing each signal to indicate approach when the line wires for that signal are energized by current of the opposite polarity; circuit means including contacts controlled by sa d polar-neutral relay for causing each signal to indicate stop-and-proceed for following trains and to indicate absolute-stop for opposing trains on that stretch of track when the circuit for the control of the polar-neutral relay for that signal is opened; a neutral relay for each signal; circuit means including contacts of the polar-neutral relay of the signal in advance for energizing each of said neutral relays when the next signal in advance for governing traffic in the same direction indicates clear or approach-medium, pro- Viding there is a train in said stretch of a single track approaching the signal under consideration,

through a circuit including a line wire for the control of a polar-neutral relay for an opposing signal; and circuit means including contacts of said polar-neutral relay and said neutral relay for causing each signal to indicate clear when said polar-neutral relay and said neutral relay for that signal are both picked up.

4. In an absolute-permissive block signaling system for railroads, a stretch of single track having signals for governing trafiic in both directions; a pole changing relay for each signal controlled in accordance with the occupied condition of the track in advance of that signal; a stick relay for each signal energized only if a train has accepted that signal and has not yet passed the next signal in advance; circuit means including contacts of said pole changer relay and said stick relay for causing lamps indicating stop-and-proceed to be illuminated when said stick relay'is picked up, if said pole changer relay for that signal is in a dropped-away position; and circuit means including contacts of said pole changer relay for causing lamps indicating absolute-stop to be illuminated when said stick relay and said pole changing relay for that signal are both in a dropped-away position.

5. In an absolute-permissive-block signaling system; the combination with a single track sec tion; a plurality of signals for governing trafiic in each direction over said section; a stick relay for each signal; a pick-up circuit for each stick relay closed only when a train passes the associated signal in the direction it governs traffic; a stick circuit for each stick relay closed only so long as the block in advance of the associated signal is occupied; a polarized home relay for each signal energized by current of one polarity if two blocks in advance are unoccupied, energized by current of reverse polarity if the block in advance is unoccupied and the stick relay associated with the signal in advance is energized, and deenergized if the block in advance is occupied; a special relay also governed in accordance with traffic conditions in advance; circuit means including contacts on said home relay, said stick relay and said special relay for governing the associated signal; and means including the home relay for a signal governing traflic in an opposite direction which will be deenergized by a train entering the said section in the normal direction for causing a signal for the normal direction of travel to give an indication in accordance with the condition of indication of said home relay said stick relay and said special relay for that signal.

6. In an absolute-permissive-block signaling system; the combination with a single track section; a plurality of signals for governing traffic in each direction over said section; a stick relay for each signal; a pick-up circuit for each stick relay closed'only when a train passes the associated signal in the direction it governs traffic; a stick circuit for each stick relay closed only so long as the block in advance of the associated signal is occupied; a polarized home relay for each signal energized by current of one polarity if two blocks in advance are unoccupied, energized by current of reverse polarity if the second block inadvance is occupied and the stick relay associated with the signal in advance is energized, and deenergized if the block in advance is occupied; other means for controlling each signal; and approach control means for each signal to cause proper indication of such signal by said home relay and said other means when there is a train approaching such signal including a home relay for a signal governing traflic in the opposite direction.

7. In an absolute-permissive-block signaling system; the combination with a stretch of single track; a plurality of successive signals for governing traffic in each direction over said stretch; a polarized home relay for each signal; a pair of wires for each signal extending to the next signal in advance; means including said home relay for each signal to cause such signal to give three aspects depending on whether the associated home relay is energized by current of normal polarity over the associated pair of line wires, is energized by current of reverse polarity over the associated pair of line wires or is deenergized; and means for causing each signal to give a fourth aspect including one of the wires of the pair of line wires for said signal extending to the next signal in advance and one of the line wires of a pair of line aires associated with a signal for governing trafic in the opposite direction.

8. In an absolute-permissive-block signaling system; the combination with a stretch of single track; a plurality of successive signals for governing traflic in each direction over said stretch; a polarized home relay for each signal; a pair of wires for each signal extending to the next signal in advance; means including said home relay for each signal to cause such signal to give three aspects depending on whether the associated home relay is energized by current of normal polarity over the associated pair of line wires, is energized by current of reverse polarity over the associated pair of line Wires or is deenergized; and means for causing each signal to give a fourth aspect including a special relay; and an energizing circuit for said. special relay including contacts of the home relay next in advance closed only if such home relay in advance is energized by current of normal polarity and including contacts closed only if the home relay for the adjacent signal governing trafiic in the opposite direction is deenergized.

9. In an absolute-permissive-block signaling system; the combination with a stretch of single track; a plurality of successive signals for governing traflic in each direction over said stretch; a polarized home relay for each signal; a pair of wires for each signal extending to the next signal in advance and including front contacts of track relays of the block extending from such signal to the signal next in advance; means including said home relay for each signal to cause such signal to give three aspects depending on whether the associated home relay is energized by current of normal polarity over the associated pair of line wires, is energized by current of reverse polarity over the associated pair of line wires or is deenergized; and means for causing each signal to give a fourth aspect including a special relay; and an energizing circuit for said special relay including contacts of the home relay next in advance closed only if such home relay in advance is energized by current of normal polarity, including back contacts of a directional stick relay for the adjacent signal governing trafilc in the opposite direction which directional stick relay is energized only by the passage of a train in such opposite direction, and including contacts closed, only if the home relay for the adjacent signal governing trafiic in the opposite direction is deenergized.

10. In a block signaling system of the absolutepermissive block type for railroads, a stretch of single track having signals for governing trafiic in both directions by permissively governing traific to the rear of a first train and by absolutely blocking an opposing train, a polar-neutral relay for each signal, circuit means including only two line wires for each signal extending to the next signal in advance for governing traffic in the same direction for energizing said polarneutral relay with current of one polarity or another in accordance with whether the corresponding polar-neutral relay at such signal in advance is energized or de-energized through the medium of the associated two line wires from a source of current at such signal in advance, a neutral relay for each signal, circuit means including one of said two line wires for such signal and one of said two line wires for the opposing signal next in advance for energizing said neutral relay or leaving it de-energized in accordance with the distinctive polarity of energization of the polar-neutral relay for the next signal in advance governing traific in the same direction, and circuit means including contacts controlled by said polar-neutral relay and contacts of said neutral relay for causing each signal to display a distinctive indication when said polar-neutral relay and said neutral relay for that signal are both energized.

GEORGE T. CALLAHAN. 

